Recipe's barrel modes are mutable, which is not what recipes should be. Probably should make an immutable version to prevent silly issues stemming from fetching an invalid output.

I don't really know of a good way to architect this. Would every mode have an immutable version, if so serial logic becomes way more complicated. A flag would be possible, but would probably not cover all edge cases

Simply wrapping a mutable one with controlled access and copys on wrap and unwrap would work

This is also why I prefer langs like scala - they have types built around being immutable and come with extra copy fields that make it easy to change without truly changing.

This might have already been fixed. If not it will be fixed with the barrel rework in the 1.20 version